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Problem with Laminar StrictSignal.foldLeft where the accumulated value is an EventStream
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| import com.raquo.laminar.api.L | |
| import com.raquo.laminar.api.L.* | |
| import munit.FunSuite | |
| import scala.collection.mutable | |
| case class Foo(s: String) | |
| case class Bar(s: String) | |
| object Collector { | |
| def apply[A](stream: EventStream[A], operations: () => Unit*): List[A] = { | |
| val result: mutable.ListBuffer[A] = mutable.ListBuffer.empty | |
| stream.foreach { a => | |
| result.prepend(a) | |
| }(unsafeWindowOwner) | |
| operations.foreach(_()) | |
| result.toList | |
| } | |
| } | |
| object Interpreter { | |
| def interpret(foo: Foo): EventStream[Bar] = EventStream.fromValue(Bar(foo.s)) | |
| def interpretAndReconcile(foo: Foo, bar: Bar): EventStream[Bar] = EventStream.fromValue(Bar(s"${foo.s}(${bar.s})")) | |
| } | |
| class SignalTransformer extends FunSuite { | |
| def transform(foos: StrictSignal[Foo]): EventStream[Bar] = | |
| foos | |
| .foldLeft(Interpreter.interpret(_)) { case (accumulator: L.EventStream[Bar], foo: Foo) => | |
| println(foo) // Just making sure things are getting called as I expect | |
| // The order of the parameters in this merge seems not to matter. | |
| EventStream.merge(accumulator.flatMap(Interpreter.interpretAndReconcile(foo, _)), accumulator) | |
| } | |
| .changes | |
| .flatten | |
| test("StrictSignal") { | |
| val foo1: Foo = Foo("1") | |
| val foo2: Foo = Foo("2") | |
| val foo3: Foo = Foo("3") | |
| val foos: Var[Foo] = Var(foo1) | |
| // I don't usually write tests with println. I'm just using munit to run this. | |
| println( | |
| Collector( | |
| transform(foos.signal), | |
| () => foos.set(foo2), | |
| () => foos.set(foo3) | |
| ) | |
| ) | |
| // What I get is: | |
| // Foo(2) -- this is from the println in the foldLeft | |
| // Foo(3) -- this is from the println in the foldLeft | |
| // | |
| // List(Bar(1), Bar(2(1))) -- this is from the collected output | |
| // What I want is (ignoring the two 'Foo' output lines): | |
| // List(Bar(1), Bar(2(1)), Bar(3(2(1)))) | |
| } | |
| } |
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